The present invention relates to a high frequency antenna tuning device. It applies to the tuning of a high frequency antenna connected to a transmitter-receiver able to periodically supply power signals at frequencies predetermined by an interface. This antenna can be carried by a vehicle, whose movements over a territory it is wished to follow from a position fixing station, the transmitter-receiver supplying the aforementioned signals also being placed on the said vehicle. This type of position fixing is for example described in French patent application No. 84 03539, filed on Mar. 7th 1984 in the name of the present Applicant.
It is known to tune a high frequency antenna connected to a transmitter periodically supplying signals at frequencies predetermined by an interface. For this purpose use is made of a variable capacitor or capacitors having different values, connected to one end of the antenna. These capacitors are switched as a function of the frequency of the different frequency signals supplied by a transmitter-receiver. When these signals have a high power level, switching from one capacitor to the other may destroy the capacitors or even damage the transmitter-receiver, when it takes place during the transmission of said power signals.